Process for vulcanizing auto tires



April 27 1926.

Filed Oct. 16 1922 ATTORNEX Patented Apr. 27, 1926,

PATENT OFFICE.

WALTER L. FAIRCHILD, OF NEW YORK, N. Y.

PROCESS FOR 'VULCANIZING AUTO TIRES.

Application filed October 16, 1922. Sryial No. 594,766.

10 vulcanizing automobile tires, and more specifically aims to provide a process by means of which a tireshoe may be Vulcan;

izcd simultaneouslyon its interior and exterior surfaces.

. in myr 'previous-application for U. S. Letters Paternt filed December 10, 1921., Serial N0.--21 '.391 entitled FVulcanizing apparatus Ishowed a device by means of which hollow articles, such as inner tubes may be vulcanized in a single operation, and in the final form iniwhich they are to be used. In that application I disclosed means by which the inner tube was placed in the machine in its final form as a closed ring, and there vulcanized without the use or a mandrel. In

that machine the inner tube was placed'within a suitable mold, and vulcanizing gas was inttoduced under pressure, into the interior thereof, this pressure insuring that the tube wouldbe forced into complete contact with the interior surfaces. of the mold, and furthermore, making it possible by heating mold and the vulcanizing gas to.vulcanu:c*

all parts of the tire.

the tube simultaneously both from within and from without. I have found the vulcan-" izing machine which I there described suitable for use not only in the manufacture of inner tubes, but hai e also discovered that the principle on which that machine was based may also be applied tothe manufacture of tire shoes. Obviously, inasmuch ".s the tire shoe is a ring open along its inner periphery, some means must be provided by which the shoe n'ia-y be hermetically sealed so that a vulcanizing gas may be introduced into the interior thereof during the heat treatment.

As ,tire shoes are at present vulcanized, it is customary to support the shoe and 69 maintain it in contact with the inner surwhereupon the assembled parts were heated such a length of time as was necessary. The

latter development, however, substituted a collapsible air bag in lace of the metallic mandrel, this air bag 'ein constructed so that air under pressure mig t be introduced therein to keep the shoe in distended position ring the vulcanization rocess.

In the use of a solid mandre no provision was made by means of which thi'smandrel could be heated, and as 'a result the vulcaZnization proceeded from the exterior of the l tire, which was in contact with the heated" In order to make completely vulcanized, it proved to be necessary in many instances to over-vulcanize the tread portion, and'under the best conditions it was impossible to insure an even vulcam ization of the shoe throughoutthe various layers. In the case of the airbag, a some-' what superior result was obtained, the air bag permitting sufiicient pressure to be placed interiorly of the shoe to insure that all parts of the tread would'lie in contact with the mold, but these air bags were an add ed source of expense, while not entirely obviating the difiiculties previously pointed out. One of the objects of this invention, the'refore, is to provide a process by means of which a tire shoe may be vulcanized, the vul mold, wardly toward that-portion in con tact with the mandrel. sure that the inner portions of a shoe were canization. taking place evenly throughout '.Anot her object of theinvention is to 'pro-' vide a: process for vulcani'zmg ,tire shoes by means of which the shoe may be vulcanized simultaneously both on its exterior andinterior surfaces. I

Another object of the invention is to provide a process by which a tire shoe may be evenly vulcanized both from within and from without, the progress of the vulcanization being at allv times under exact control. A further object'of the invention is to provide a process by means of which the entireshoe may be vulcanized, the vulcanization process being carried on under exact control, and without the necessity of provid-. ing an interior support for the shoe.

Another object of the invention is to provide a process by means of whichthe shoe may be evenly vulcanized throughout its thickness without the necessity of providing an-drels, air bags, or other means by which shoe Will be held in contact with the 1. 1 e

E0; sumac-es of tne mold.

Another object ofthe invention is to proe a process by means of which the vulcaniaation of a tire shoe may be cheaply and inexpensively carried on, this process being under the exact control at all times, whereby the progress of the vulcanization may be regulated as desired.

Another object of the invention is to provide a process for the vulcanization of a tire shoe, by means of which the vulcanization process may be carried on both from the interiorand exterior of the carcass, thereby greatly shortening the length of time necessary for the exposure of the shoe to the heattreatment and obviating the expense of shoe supporting means.

Another object of the invention is to provide a process by means of which a tire shoe may be vulcanited, the shoe being supported in the mold in such a way as to provide a closed chamber, whereby the vulcanizing may be carried on both on the interior and exterio'r surfaces of the shoe, this process being under complete control at all times, so that the rate of vulcanization may be regulated, and furthermore, being inexpensive to operate, and requiring no expert attention.

Other objects and aims of the invention, more or less specific than those referred to above, will be in part obvious and in part pointed out in the course of the following description of the elements, combinations, arrangements of parts and applications of principles, constituting the invention; and the scope of protection contemplated will be indicated in the appended claims.

In the accompaying drawing, wherein I have shown preferred forms of embodiment of my invention: s

Figure 1 shows a view in perspective of a portion of the shoe, together with the means y which the face is hermetically sealed.

Figure 2 is a view in perspective, showing a section of a tire held Within the mold.

Figures 3, 4;, 5 and 6 are cross-scctional views of a shoe, showing'one type of the means by which the shoe is hermetically sealed. e a

Figures '1', 8, 9 and 10 are cross-sectional views of a shire showing-a modified type of means by which the shoe is sealed.

Figure 11 is a cross-sectional view through 1 a mold, showing the shoeposition'ed in place therein and sealed; and

Figure 12 is a View in perspective of one form of sealing means.

Referring now to the drawing, wherein similar reference characters refer to similar parts throughout the several views thereof, the reference character 1 indicates the carcase or shoe of a tire, formed with a thickened tread portion 211ml a pair of 3 releases those beads being spaced apartso that the cross-sectional contour of the shoe is similar to that of a horseshoe. The beads, as indicated, are ordinarily thickened and provided with interior reinforcing means at the point indicated by the reference character l, the beads being further provided with flattened surfaces 5, which surfaces are adapted to lie in contact with the rim when the shoeis mounted in position.

As has been briefly explained above, the principle of this invention depends upon the introduction of a vulcanizing gas of suitable chemical composition into the interior of the shoe, while the latter is positioned within the mold. As is indicated in Figure 11, the mold customarily consists of a pair of coop erah ing members 6 and 7, which are provided with deep opposed recesses adapted to form a chamber for the shoe when the members are placed in opposed relation. In the former vulcanizing processes, the core or mandrel about which the shoe was laid, toge her with the shoe thereon, is placed in the recess in one of the mold members. The second mold member is then laid thercover, and forced in position, whereupon the mold members are clamped together and the whole mold, with, the shoe therein, placed in a heating oven or vulcanizing chamber. Instead of using a solid core mandrel, it has also been the practice to strip the shoe from the mandrel on which it is formed and toinsert a collapsible bag within it, air under pressure being introduced into this bag, so as to force the shoe into contact with the mold, In the case of shoes which are to be provided with a roughened or cornugated tread surface, such as known as\th'e non-ski'd tire, the inner surface of the mold is rovided with suitable depressions into which these corrugations may fit, sothat the interior structure of the mold will determine the character of the exterior surface of the tire.

In the present invention I desire to make use of the principle of introducin a vulcanizing gas which is heated and under pres sure, into the interior of the shoe, this gas providing means not onlyfor keeping the shoe in distended position against the in- -terior faces of the mold, but furthermore,

providing means by which the interior surfaces of the shoe may be vulcanized. By

. such an arrangn'icnt it is possible to carry on the vulcanization evenly, both interiorly and exteriorly of the carcass. Obviously, such an arrangement will greatly reduce the length. of time necessary for a vulcanization process, and furthermore, will save air bags, or mandrels, which are a considerable item of expense.

As an additional desirable feature, the introduction of a heated vulcanizing gas makes it possible to regulate exactly the speed atwhich the vulcamzing process takes place. While I have shown in the drawteriorly and interiorly of a shoe. Inasmuch as the shoe is not a closed body. it is necessary to provide some means, which will be applied to the flat surfaces of the beads,

so as to make the shoe a closed chamber. 1'

provide several ditl'erent types of sealing means in two modified forms, as shown in the drawings.

In the simplest form I may use for scaling :ur ses a thin stri of raw rubber illns= trated at 8 in Figure 1. This rubber will be placed in contact with the flat surfaces of the beads, and by reason of the strip and the shoe being formed of rubber in the raw condition, the two will adhere. As i= shown in Figure 3, it is necessary to provide some nieans tointroduce the vulcanizing gas usually steam into the interior of the shoe, and l, therefore, provide the strip with '1 plurality of inlets 9, which may be positioned at any suitable place in the strip, the mold being provided with a suitable channel through which these inlets punect. One inlet may be used if desired but I preter to in.

troduce the vulcanizing' gas through a. plurality of inlets connected to a common source of gas. I also provide one or more outlets similar to inlet 9 but provided with pressure control valves so arranged that the gas may circulate through the interior of the shoe while the pressure is maintained. The conduit for the vulcanizing gas will be connected to the inletand the conduit is provided with valves by which the flow of gas into the shoe may be controlled. As is shown in Figure, 3, the edges of the strip register with the edges of the bead, although .i show a. slightly modified form in Figure 4, in which the strip is. intended to overlap the edges of the bead slightly, as shown at l0. Either, of these forms may be used, the

. method of application being the same.

lVith the strip applied, as is indicated in Figure. 1, the shoe is iutiodiued into a mold in the usual manner, and with the two halves of the mold clamped in position, the

heating medium is introduced into the heating jacket for the mold. Ashes previously been explained in my prior application, means is prmided to exhaustthe interior of the shoe, andatter this exhaustion has taken place by connecting the inlet 9 to a vacuum pipe. the heated vulcanizing as is introportion by the contour of the mold.

duced into the closed chamberformed by the shoe and the strip. The heating of the mold is then carried on such a length of time as is necessary, the shoe being vulcu iz-ed equally on its interior and exterior surfaces. Obviously, the strip, which JS of raw inbbcr, will be vulcanized to the beads, and

when the vulcanization is completed, the

shoc will be withdrawn from the mold and the sealing strip cut away. It is not necessary to remove the strip entirely since it will bemade of thin material, but,.i"l desired, only that portion of the strip which lies between the beads maybe cut away, the per, tions of the strip overlying the beads being left in place. This will interfere in no way with the utilityo't the shoe, as will be obvious. 1

The same principle of operation applies to the strip shown in Fi ure 4, the/strip in this form providing: a slightly better scal. In Figure 5 there is shown adu'l'erentform ofstrip, winch maybe here constructed of textile material, such as webl'iinp;- The surfaces of this fabric may be coated with raw rubber, if desired so that the strip will adhere.

to the bead, althpugh the uncoated web will work equally well. The strip used in the same manner as has previously been de scribed, but may be more readily torn from the bead, whereupon the, strip of webbing may be again coated with raw rubber and used an indefinite number of times. In the form shown in Figure 6, the. strip is made of a fibrous material which is somewhat elas-fl.

pressed into position against the flat surfaces of the bead, a portion thereof,- indicated at 11, will project a slight distance iii-- to the interior ofthe shoe, this insuring a tight contact at the'pointed edges of the bead, sealing.

thereby making more secure the lathe forms of sealing strip shown in the rcnn'iiuing figures, I use'a metallic ring, as indicated by the iuuneral- 12, which is provided with the customary form of inlet 13, and has flat surfaces l i along either edge. Between the flatsurlaces the strip projects into the interior oi the shoe slightly, as at 15, the outline of this projecting portion bclug similar to a keystone. The projecting portion has inwardlyextending channels on either lateral surfac, into which the pointed edge of the bead may extend. T his metallic ring will lf'e pcsitioncd in the manner indicated in Figure 1].. as at 16. and is of such size that the shoe will be forced into the channels on either side of the projecting The process (if-vulcanization is carrieoleon in the same manner as before, the pressure of the vulcanlzmg gas insuring that the head will lie firmly in contact with the str p so as to prevent the escape of the gas under pressure.

In the form of strip indicated in Figure I 8, it will be seen that the strip is provided with sharp circumferential ribs 17, these being adapted to project a short distance into the face of the bead, thereby insuring that the head will be held firmly in position, and furthermore, providing a better seal. It will be understood,.of course, that the sealing means is ordinarily applied before the shoe is introduced into the mold, the two being placed in position together. If desired, however, I may use a flat strip, such as is shown in Figure 9 at 18, this type of strip being cheapest to construct and serving its urpose equally,- with those previously shown,

ing slightly less convenient to handle, however.

In the form shown in Figure 10, I provide a ring similar to that shown in Figure 9.

but preferably place a layer of material on the inner side'of the strip which is to lie in contact with the beads. This strip of material, indicated at 19, will be somewhat similar to the strip shown in Figure 5, that is to say, it may e in the form of a layer of textile material, suitably impregnated with raw rubber, if desired.

Figure 2 illustrates the manner in which the sealing ring is to be mounted in posi-.

tion, and Figure 11 illustrates an alternative form of sealing ring which may be used in connection with the oldform of mold. In that type the mold members did not contact with each other along the interior surfaces of the shoe, but were spaced apart, as is indicated at 20, so as to permit of an extending portion of the core to lie therebetween. The sealing means used in conneetion with such mold forms will necessarily have its outer surface shaped so as to conform to the shape of the mold members, and has, therefore, a projecting portion which lies between the mold members. The surface of the strip which contacts with the edges of the bead, however, is preferably in one of the forms illustrated in Figures 7 to 10 inclusive.

In Figure 12 I show a ring somewhat similar to that illustrated in Figure 10, be ing constructed of a metallic portion 21, which is faced with a layer of material, such as is illustrated in Figure 10. This layer 22 may, if desired, be provided with attaching means illustrated at 23, to hold the strip in contact with the face of the ring. As is shown at 2-1, the ring is not closed, but at its ends is provided with overlying portions so that the ring is capable of slight expansion. being very similar to the common formofpiston ring. The gap may be constructed in various ways as desired. This spring ring will be used in the same manner as has previously been described.

When the shoe has been placed in the mold with the ring in position, and the second half of the mold forced in contact therewith, it will be seen that the shoe forms a closed chamber, capable of confining the gas which is to be used for the vulcanization. This gas, as I have stated, will be preheated, and will be of a chemical character, which will assist in the vulcanization process.

It will be seen then th t by the process which I have here set forfhfit is possible to vulcanize the shoe, both on its interior and exterior surfaces, without the necessity of roviding mandrels, air bags, or other means y which to maintain the shoein'contact with the inn er faces of the mold; Furthermore, by vuleanizin the shoe on its inner and outer faces simul t time from which the heat treatment is to be continued. will be greatly shortened, and the rate at which the vulcanization is to progress, may also be closely regulated. It will be understood that in some cases the rapid vulcanization is entirely satisfactory, while aneously, the length of in others, the character of the rubber is v such that it would be preferable to vulcanize slowly for a considerable period of time. Either of these conditions may be readily established by my process. The shoe is in its final form when vulcanization is complete, except for removing the sealing strip. In the event that a metallic strip is used, this may be quickly slipped from place, while if a strip made of raw rubber is used, as has been explained in connection with Figures 3 and 4:, it will be necessary to cut the strip or remove a portion between the beads. If the ligated fabric is used, this may be easily torn away. Either of these operations is simply and easily carried on. This process is inexpensive, owing to the saving in the period of heating, and also saves the expense of air bags, these being capable of use only a few times, and being much more expensive than a strip of raw rubber, which I'use for sealing purposes.

Obviously, the metallic rings which I have shown as an alternative form of sealing means may be used indefinitely. While I have shown the mold members of theold form in which the mold with the article therein are to be placed in an oven, it will be clear that I may use individually heated mold members as reviously described. I do not desire, there ore, to confine myself to any particular type of m0ld,'sinc.e my process will be-satisfactorily operated with any of the present known forms.

As' many chan es could be made in this construction wit rout departing from the scope of the following claims, it is'intended that all matter contained in the .above description or shown in the accompanying drawings shall be interpreted as illustrative only and not in a limitin sense.

Having thus describe my invention, what I claim as new and desire to secure by Letters Patent is:

1. A process of the class described which consists in applying a strip of raw rubber to the beads of a shoe thereby closing-the space between the beads and sealing the interior of the shoe, confining the shoe and the strip in a detachable mold, vulcanizing the shoe and strip by introducing steam interiorly, removing the mold and cutting away the strip between the beads.

2. A process of the class described which consists in applying a strip of raw rubber to the beads of a shoe thereby closing the space between thebeads and sealing the interior of the shoe, backing the strip externally with a heavier annular member, confining the shoe and strip andbacking member in a detachable mold, vulcanizing the shoe and strip by introducing steam interiorly, removing the mold'and backing member and cutting away the strip between the beads.

3. A process of the class described which consists in applying a sealing strip to the beads of a shoe whereby to seal the interior thereof, confining said sealed shoe within' a mold, introducing avulcanizing gas into the interior of said shoe, heating said mold whereby to vulca'nize said shoe, and to cause said sealing means to adhere to the beads thereof, removing said mold and separating said means along a line parallel to andbetween the edges of said beads.

4. A process of the class described winch consists in applying sealing means to the beads of a shoe whereby to cause the latter to form a closed chamber, confining said sealed shoe within a mold, introducing a vulcanizing gas under pressure into the interior of said sealed shoe while heating said mold discontinuing the application of'he'at an beads.

5.. A process of the class described which consists in applying a rubber sealing strip to the beads of a shoe, confining said sealed shoe within a mold, introducing a vulcanizing means-along aline parallel to,

'ing gas under pressure into the interior of t consists in uniting the beads of a shoe by means of a strip whereby to seal the interior of said shoe, confining said sealed shoe within a mold, causing a vulcanizing gas to circulate withinsaid shoe under pressure, heat ing the exterior surface'of said shoe, discontinuing said heating and said circula--- tion, removing sa1d shoe from said mold,

and dividing said sealing meansinto two parts along a line passing between said beads. i

7. A process of the class described which consists in uniting the beads of a shoe by means of a strip whereby to seal the interior of said shoe, confining said sealed shoe within a' mold, causing a vulcanizing gas to circulate within said shoe under pressure, heating the exteriorsurface of said shoe, discontinuing said heating and said circulation, removing said shoe"'from'said mold, and removing that portiolr'of said strip ly-. ing between the inner edges of saidbeads.

In testimony whereof, I atfix' my sign-a-v ture.

WALTER L. FAIR CHILD. 

